[Bug libstdc++/66146] call_once not C++11-compliant on ppc64le

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66146

--- Comment #7 from Martin Sebor <msebor at gcc dot gnu.org> ---
I opened http://sourceware.org/bugzilla/show_bug.cgi?id=18435 for the glibc bug
and attached a lightly tested patch to it.